Motorcycle Repair: yamaha xs 1100 1980, yamaha xs 1100, accurate diagnosis

Question
I have a Yamaha xs 1100 which has been keep outside for three years and not been used and now i wont to ride it again the i have cleaned the carburetors and cleaned the fuel tank new spark plug new cdi unit . but the bike starts fine but when i am riding the bike it misfires and a lot of black smock comes from the exhaust i have checked that the spark plugs sparking and they are but the spark plugs are very black in colour could you help me out        thanks very much regards nick

Answer
This could be due to a great number of things, but most likely because its running too rich (too much fuel) If a jet fell out, wasn't installed, or the air/fuel mix is set too rich this can happen. Id have to hear the bike run to give you a more accurate diagnosis so i appologize for the inadiquate info..

Hope this helps!

~Mark